Device for manufacturing thinwalled containers open at one end



Dec. 17, 1946. KELLER 2,412,813

DEVICE FOR MANUFACTURING THIN-WALLED CONTAINERS OPEN 'AT ONE END INVENTORJ Jakob Keller the arrangement of Patented Dec. 17, 1946 UNITED STATES PATENT. OFFIC DEVICE FOR MANUFACTURING THIN- glilglLED CONTAINERS OPEN AT ONE 1 Jakob Keller, Zurich, Switzerland Application August31, 1944, Serial In Switzerland May 3, 1944 2 Claims.

Containers open at one end are already made by deep are cylindrical in shape is a circular tin disc, which is drawn by a draw-punch through a manner that the thickness of the walls is reduced while the container is drawn out by a single puncheon.

This process can be successfully exploited for materials with a high degree of toughness, while the manufacture of containers open at one end the container on entering the next ring.

In the accompanying drawing, Fig. 1 depicts the single ring dies, while Fig. 2 is a cross-section of an example of the device with three ring dies. The following is a description of the invention in greater detail in relation to the drawing. a

Punch 8, which is precisely cylindrical, forms with die A and rim-holder a a drawing tool, which does not differ from the tools of this type already in use. It follows that can E, with a depth equal to a, is produced in the usual way.

Before its open end leaves the drawing surface of die A, can E (whose depth is a) is carried by punch S into ring die B which draws the wall of the can to a depth equal to b. The second ring 2 die C is separated from the first ring B by distance-ring f. and the interval between them is such that the upper edge of the can, whose depth is now b, is still engaged in ring B, when its bottom already penetrates into ring C. The depth of the can-previouslyequal to b-is in the same way increased by its passage through ring C to c.-

In like manner the action of the third ring die D draws the depth 01 the can from c to d. The thickness of the two distance-rings f and f selfiarating ring dies B, C

in turn proportionate to the decrease of the thickness of its walls caused by each drawing process.

In Fig. 2 die A, ring distance rings f and f and stripping-ring a. are combined in holder h to form the deep-drawing tool which is the object of the invention.

At the instant the container enters the first ring dies, the material speed as the punch. It can be demonstrated mathematically that when leaving the ring the tin retains the speed of the punch, but that the leaving the first ring collides with that flowing back; again breakage is unavoidable. In consequence the interval must be such that the container enters the second ring die only when the work of the first ring die is almost terminated.

and D. is determined by the incrementof the depth of the can, which is dies B, C and D, as well as to be formed has the same The slight pressure that still occurs will then have the useful function of loosening the wall of the can from the punch.

- More important than thisfloo'sening] action is, however, theyg'uiding in the second ring die. The purpose of the process to which the invention relates is'the manufacture orcontainers with vwalls a few tenthsof a millimetre thick. The centering toleranceis, in consequence, of the order of 1/100 mm., i'.. e. of the orderof sr'nall, and even negligible, deformations.

hand, vto increase the working speed, it is of interest that the stroke of the punch should be assmall as possible. A limited degree of overlapping of successive operations offers the further advantage of a process smooth and free from shocks; and it is obvious that, owing to the thinness of the containers walls, even slight shocks result in breakage. v

Thorough experiments have proved thatthe best results are obtained with a pressure arising through an interval between the rings 10% smaller than the corresponding, depth of the can. Particularly favourable results have been achieved in the manufactureofaluminium cans.

This is most probably due to the fact that in the On the other 7 process to which the invention relates shaping is eflected simply by the strain caused-by-the reciprocal action of ring and punch; and aluminium can be shaped under the effect of this strain, not only with exceptional ease, but also v very uniformly. f I y Essential for the success of the process isalso the profile oi the, ring dies. Repeated experiments have proved that the best results are achieved. with a lateral angle of 10:3".

' 1. A device for manufacturing thin-walled containers open at one end, in which the raw material is drawn in the usual manner by a single punchfirst through a, deep-drawing die and then through a. series ofi ring dies, all of the ring dies being of uniform internal diameter, said device characterised in that the first ring die is so fitted that the container, on entering thi ring, isstillwithin the upper part of the deep-draw ing die, and that the successive ring dies are arranged at intervals from each other equal to at least 90% of the depth of the container at the entrance to the next ring.

, 2, A device according to claim 1,' characterised in that the ring dies have a lateral angle of 10:3?

flaring outwardly from their bottom to their top surfaces.

-' JAKOB KELLER. 

